1. Field of the Invention
The present invention relates to a film-forming composition, a method for manufacturing the film-forming composition, a diffusing agent composition, and a method for manufacturing the diffusing agent composition.
2. Description of the Related Art
According to the related art, for example, in manufacturing a solar cell, an N-type impurity diffusion layer is formed in a semiconductor substrate by applying a diffusing agent that contains an N-type impurity-diffusing component to a surface of the semiconductor substrate so as to form a film of the diffusing agent and then by causing the N-type impurity-diffusing component to diffuse from this film. Conventionally, as a method for forming a film of a diffusing agent on the surface of a semiconductor substrate, a spin coating method has often been employed where a coating liquid containing the diffusing agent is applied by a spin coater or the like.
However, in recent years, there is a need for cost reduction, high throughput, and reduction in environmental burden in semiconductor manufacturing related fields, particularly, solar cell manufacturing fields. More specifically, there is a need for reducing a used amount of a coating liquid for diffusion and partially forming regions with different diffusion carriers and diffusion concentrations, i.e., achieving partial diffusion, in a single substrate with a fewer number of steps. In this case, there has been a problem, in a conventional spin coating method, where the amount of a coating liquid used for each substrate is large, increasing the cost as well as the amount of a waste liquid. In partial diffusion, since it is necessary to form a diffusion protection film or the like in advance on a substrate by using a photolithography method or the like, there has also been a problem where the number of steps increases.
On the other hand, there has been suggested a method for partial diffusion by partially applying a diffusing agent on the surface of a semiconductor substrate by using an ink-jet method (see, for example, patent document Nos. 1-3). In an ink-jet method, a diffusing agent is selectively discharged from an ink-jet nozzle to an impurity diffusion layer forming region for patterning without using a mask. Thus, as compared with conventional spin coating methods, the ink-jet method does not require a complicated step and makes it possible to form a pattern easily while reducing the amount of liquid to be used.